Internal combustion engine



Sept. 24, 1940. o. LESER ET AL f 2,216,083

INTBRNAL couusTIoN ENGINE Filed oct. 22. 19:58

Patented Sept. 24v, 1940 PATENT AOFFICE INTERNAL COMBUSTION ENGINE OttoLeser, Alexander Garve and Oskar Kurtz,

Augsburg, Germany,

assignors to Maschinenfabrik Augsburg-Nrnberg A. G., Augsburg, Germany,a corporation of Germany Application October 22, 1938, Serial No.236,530 Germany October 22, 1937 7 Claims;

This invention relates to two-stroke cycle combustion engines havingprovision for scavenging the combustion gases from the engine cylinder.

One object of the invention is the provision of a two-stroke cyclecombustion engine in which the cylinder wall is provided with slotsthrough which scavenging air is supplied when the Aslots are uncoveredby the piston, the slots being so arranged as to cause the cylinder tobe supplied with air streams that are successively tangent to a circlelocated eccentrically of the cylinder axis and so arranged as toeffectively scavenge the exhaust gases from the cylinder.

Another object of the invention is the provision of an engine of thecharacter mentioned in which there are a plurality of rows of annularlyspaced scavenging air' slots, the streams of air from one row of suchslots being directed successively tangential to a circle locatedeccentrically of the cylinder axis while the streams of air from anotherrow of slots are successively tangential to another circle eccentric ofthe cylinder axis and displaced around the cylinder axis from the firstcircle mentioned.

Another object ofthe invention is the provision of an engine of thecharacter mentioned having a plurality of rows of scavenging air slotsarranged for the supply of scavenging air streams tangential todifferent circles eccentric of the cylinder axis, the slots ofthedifferent rows having different inclinations with respect to a planetransverse of the cylinder axis so that the circles to which the slotsof the different rows are tangentially arranged will be displacedaxially of the cylinder further than the axial displacement of the rowsof slots themselves.

Another object of the invention is the provision of a two-stroke cycleengine having a plurality of rows of annularly spaced scavenging airslots provided in the cylinder wall and adapted to be uncovered by thepiston when near the end of its working stroke, the various slots beingso arranged as to direct scavenging air streams from opposite sides ofthe cylinder axiscooperating to produce a number of whirling actionse'ective in preventing the retention of a core or cores of the exhaustgases. f

Other objects and advantages of the invention will be apparent from-thefollowing description, the appended claims, and the accompanyingdrawing, in which:

Fig. 1 is a vertical central sectional view through the working cylinderof an engine, enibodyiag the present invention;

Fig. 2 is a. transverse section taken 2-2 of Fig. 1;

Fig. 3 is a transverse section on the line-S of Fig. 1; and

onA the line Fig. 4 is a transverse section on the line 0f Fig. 1.

Referring more particularly to the drawing by reference-numerals, Idesignates the cylinder of an internal combustion engine of thetwo-stroke cycle type in which the fuel is supplied through 10 asuitable fuel inlet means such as a fuel injector nozzle l which may beof any suitable construction. Within the cylinder is a piston 6 which isadapted to successively uncover rows of scavengin'g air ports or slots2, 3 and 4 when near 15 the end nf its working stroke. Air is suppliedunder pressure through these scavenging air ports and exhaust gas isexhausted through a suitable exhaust opening which, as shown, isprovided in the cylinder head. Two exhaust 20 openings are showncontrolled by exhaust va-lves 5 which may be of the pODpet or any othersuitable type, automatically controlled at the proper Atime lin thesequence of operations in the customary manner.

As will be seen from Fig. 2, the scavenging air slots 2 are arranged onall sides of the cylinder axis, being spaced annularly and so arrangedthat the mid lines of the slots will be tangent to a circle that iseccentric of the cylinder axis, the mid lines of the successive slotstouching the eccentric circle successively so that the whirling actionthey create will be a cumulative one.

The row of slots 3 is axially displaced with respect to the slots 2,slots 3 being also so arranged 35 as to supply scavenging air streamsthat are tangential to an eccentric circle, but this circle is displacedaround the axis of the cylinder with respect to the tangent circleillustrated in Fig. 2.

'Ihe row of slots 4 which are last uncovered 40 by the piston are soarranged that the mid lines Aof the slots are tangential to a circlelying eccentrically of the cylinderaxis as will beseen from Fig. 4, andfrom Figs. 2, 3,-and 4 it will be noted that the whirling actionproduced by the different rows of slots will be centered at differentpoints that are regularly spaced around the cylinder. Where there arethreerows' of slots, as in accordance with theA construction shown, thedisplacement of the circles to which the scavenging air streams areeccentric will'be 120. Thus any core of exhaust gas that tends to remainin the cylinder within any circulating and upwardly spiraling air streamwill be eectively scavenged, as a number of spirally ascendingscavenging clr- 66 culating streams are produced, corresponding to thenumber of rows of slots, all the streams circulating in the same generaldirection of rotation but being focused about different points.

The slots 4 which are last uncovered by the piston, as will be seen fromFig. l, provide scavenging air streams that are directed substantiallyparallel with the top of the piston and have a cooling eiect on thepiston. The streams coming from the slots 3 are directed angularlytowards the cylinder head so that the circle to which the streams comingfromlthese slots is tangent will be axially disposed from the tangentcircle illustrated in Fig. 4 at a considerably greater distance than thespacing between the rows of slots 3 and 4. The slots 2 have their midlines inclined upwardly towards the cylinder head at still a greaterangle so that the circle to which the slots 2 direct their streams willbe considerably displaced in a direction axially of the cylinder.

As will now be apparent, the several whirling actions focused at severaldiierent points will effectively remove all of the burned gases and willnot permit a core of exhaust gas to remain as might be the case if asingle row of slots were provided to give a circulating effect aroundthe cylinder axis. The scavenging action produced in accordance with thepresent invention is obtained without having the several whirlingactions produce objectionable dist rbance contrary to the generalcirculating movement, as the whirling action produced by one row ofslots does not interfere substantially with the whirling action producedby the next series of slots, the result being that as the burned gasesare carried upwardly towards the head of the cylinder and any smallcores of exhaust gases that might tend to remain in the midst of anyascending air stream will be carried along by the circulating action ofthe other streams.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A two-stroke cycle engine of the character described comprising acylinder having an exhaust opening adjacent one end of the cylinder andhaving a plurality of rows of annularly spaced scavenging air slotsinthe cylinder wall adapted to be uncovered by the piston when near theend of its working stroke and remote from the exhaust opening adjacentthe other end of the cylinder, the slots of each row having' theirmiddle lines so arranged as to cause air streams to be directed from allsides of the cylinder axis and into the cylinder substantiallytangential to a circle of substantial diameter located eccentrically ofthe cylinder axis the circles corresponding to the different rows ofslots being displaced annularly from one another around the cylinderaxis with each circle arranged entirely at a side of the cylinder axis.

2. A two-stroke cycle engine oi' the character described comprising acylinder having an exhaust opening and having a plurality of rows ofannularly spaced scavenging air slots in the cylinder wall adapted topeuncovered by the piston when near the end of its working stroke, theslots of one row having their middle lines so arranged as to besuccessively tangential to a circle located eccentrically of thecylinder axis to create a whirl in one direction and the slots ofanother row having their middle lines so arranged as to be successivelytangential to another circle located eccentrically ofthe cylinder axisand displaced from the iirst circle around the cylinder axis to create awhirl in the same direction as the whirl created by the slots of thefirst row.

3. A two-stroke cycle engine of the character described comprising acylinder having an exhaust opening in the cylinder head and having aplurality of rows of annularly spaced scavenging air slots in thecylinder wall adapted to be uncovered by the piston when near the end ofits working stroke, the rows of slots being displaced axially of thecylinder, the middle lines of the slots of each row being arrangedsuccessively tangent to a circle located eccentrically of the cylinderaxis and the eccentrically located circles for successive rows of slotsbeing successively disposed about the axis of the cylinder, the slots ofthe different rows creating whirls having the same direction ofrotation.

4. A two-stroke cycle engine of the character described comprising acylinder having an exhaust opening in the cylinder head, means operableto close said opening, said cylinder having a plurality of rows ofannularly spaced scavenging air slots in the cylinder wall adapted to beuncovered by the piston when near the end of its working stroke, therows of slots being displaced axially of the cylinder, the middle linesof the slots of each row having a substantially even spacing apart andbeing arranged successively tangent to a circle located eccentrically ofthe cylinder axis, with the slots of successive rows creating whirls inthe same direction 0f rotation and the eccentrically located circles forsuccessive rows of slots being successively disposed at regularintervals about the axis of the cylinder and in axially spaced planes.

5. A two-stroke cycle engine of the character described comprising acylinder having an exhaust opening and having a plurality of rows 0fannularly spaced scavenging air slots in the cylinder wall adapted to beuncovered by the piston when near the end of its working stroke, therows of slots being displaced axially of the cylinder, the middle linesof the slots of each row being arranged successively tangent to a circlelocated eccentrically of the cylinder axis and theeccentrically locatedcircles for successive rows of slots being successively disposed aboutthe axis of the cylinder, the middle lines of the slots of thesuccessive rows being inclined at different angles to a transverse planethrough the cylinder so that the distance between the eccentricallylocated circles measured axially of the cylinder is greater than thedistance between the successive rows of slots.

6. A two-stroke cycle engine of the character described comprising acylinder having an exhaust opening and having a plurality of rows ofannularly spaced scavenging air slots in the cylinder wall adapted to beuncovered by the piston when near the end of its working stroke, therows of slots being displaced axially of the cylinder. the middle linesof the slots of each row beingA arranged successively tangent to acircle located eccentrically of the cylinder axis and the eccentricallylocated circles for successive rows of slots being successively disposedabout the axis of the cylinder, the middle lines of the slots of thesuccessive rows being inclined at different angles to a transverse planethrough the cylinder so that the distance between the eccentricallylocated circles measured axially ofthe cylinder is greater than thedistance between the successive rows of slots, the slots of the row lastuncovered by the piston being arranged to direct their air streamssubstantially parallel to the top of the piston.

7. A two-stroke cycle engine of the character described comprising acylinder having an exhaust valve adjacent one end of the cylinder andhaving a row of annularly spaced scavenging air slots in -the cylinderwall at the other end is located eccentrically oi' the cylinder axis,such circle being located at one side of the cylinder axis and having adiameterslightly smaller than the radius of the cylinder.

o'rro LESER. ALEXANDER GARVE. osKAR KURTZ.

